The Xisico Sentry Fan Club :)

[Zeddymon]

got it back together w o-rings, a couple over the crony says 744, 745 w27.9gr benjamin still 34ftlbs still uncleaned clip 6
i reread the thread on the bolt probe o-rings and agree there is a little catch i believe on the return through the clip, i will look forward to polishing
i did a double check on the gauge accuracy, because my tank is low-ish, i hooked up to the benji hand pump, strange i tried and the needle on the gauge would bounce @500psi when held at the bottom stroke (the hand pump was reading @29-3000 dropping to 2500ish with no click) i didn't see the rifle gauge from that viewpoint, did it again to try to stabilize the needle after degassing the pump, still same thing i was looking for the click of a disco or my corsair, less bouncy but still curiously wrong behavior, the gauge on the rifle is now in the red zone, so psi accuracy is questionable, hand pumps may be affected by a dampening effect of the fill probe and internal porting before it opens like a water hammer would act, the pump works fine with little movement on the others
still no chrony numbers in the red zone with possibly 3000psi in it as it stands now, while it is in the red zone let it sit overnight to see if it leaks

i do find it funny that i have to reset the safety every time i re-chamber a pellet, do i really have to do that! wah!

[Relentless Holiday]

Thought this looked dead sexy stock. but ya dressed it to kill Taso.....swweeeeet. 

wish they were just shooters though.  sounds like every BAM b4 though.  Buyin' a platform to tweek.  Gettin' older so I just want my trigger time.  But it's amazing to see what you guys do.

[Taso1000]

Hi All,

So I think I'm done with tuning my .25.  My goal was one magazine at full power.  I asked Mike at FDAR for a full power tune. 

From what I can see Mike opened up the ports from the valve exit, transfer port, and receiver port to .2".  There are three barrel ports 120° apart and are almost .2" also.  I didn't measure them when I had the gun apart.  Sorry.

So what did I do?  I pulled the stock hammer spring and installed a 10 pound Marauder spring I had purchased from Wicked Air Rifles about 2 years ago.  It was too stiff for what I was working on back then so I figured I would try it out since it was a thicker wire diameter than the stock spring.  I installed the spring and set the hammer spring tensioner all the way back as far as it would go and did not install its indexing screw.  With 33.95 grain JSB's and a starting fill pressure of 3000 psi I got:

728 fps @ 3000 psi
744
739
766 @ 2800 psi
776
801
797
813 @ 2600 psi
814
816
813
806 @ 2400 psi
804
801
791
778 at 2200 psi

I wanted to make more power closer to 3000 psi so I inserted two washers in between the rear of the hammer tension adjuster and the platform it moves.  This was because the adjuster threads are plastic and I didn't think they would last with the higher spring rate.

Filling again to 3000 psi and with the same 33.95 grain JSB's I got:

854 fps @ 3000 psi
852
844
842

I stopped as I was getting a descending velocity curve which meant too much tension.  So I removed one of the washers and tried again:

784 fps @ 3000 psi
803
807
826 @ 2800 psi
827
826
832
824 @ 2600 psi
819
813
805
799 @ 2300 psi

So if I fill to 2800 psi and use those first 7 shots, one mag, from 826 - 832 - 813, I get an average velocity of 823 fps, ES of 19 and a SD of 6.  33.95 grains at 823 fps calculates to 51 fpe.  Not bad!

I think that's good enough for me and the purpose of this rifle which is raccoon size pests at short range.  I could try the 2 washers and live with the descending string but that may not be good for longevity of the hammer cocking screw in the loading bolt from the increased spring tension.  Also I have not noticed any hammer bounce with the Rocker1 shroud but that doesn't mean it isn't there.  I'm not looking for efficiency, just reasonable on target energy.

Thanks,

Taso

[Hoosier Daddy]

I'm not looking for efficiency, just reasonable on target energy.

At 52 FPE, I think you found it!
Great work Taso

[Zeddymon]

those are great numbers, and great work!!!

[Relentless Holiday]

I'm not looking for efficiency, just reasonable on target energy.

At 52 FPE, I think you found it!
Great work Taso

+1    "Your blade will keeeel"

[Back_Roads]

 Nice results for sure !

[Taso1000]

Thank you Scott, Zdenek, POI and James!   

I really am surprised at how easy it was to get to make 51 fpe.  Mike M. did all the porting and I don't know if he did anything to the valve.  Since the rifle is not leaking I am not opening it up!  lol

So, the rifle cost $250, full tune from FDAR $100, shroud from Rocker1 $105, 10 lb/inch rate spring and washer $8.50.  That totals $463.  This is my first 50 fpe rifle so I don't know how it compares to the competition.  Ie. Marauder, Sumatra and Rainstorm II. 

I guess the Marauder would be the closest competitor price wise, under $400 when they're on sale.  But since I have not tuned one or really followed online what work they need to produce 50 fpe, I cannot compere them.

Now on to accuracy testing!   

Taso

[Acapulco]

Great info guys...but me needs to see a target at 100 yds.

[stalwart]

Does anyone know if the automatic safety can be disabled and be usable as a manual safety? 

Yes, I believe. I don't have a gen2 xs60 trigger group at hand to get you a pic, but, as the sentry appears to use it... and I have modded those for manual only.. it shouldn't be a problem.

[tawin]

Some more, the onboard pump in action, relief valve still to be upgraded with better screw, it is designed to bring up to charge in the field and fill the gun, this is the prototype in bolt action, did see a side lever sentry also, little bigger receiver covering some of the power wheel indications but not in the way

Any more information on the pump up Sentry? Does the pump stay on the gun or just when needed? Is it a three stage pump?

 I realize this is an older post but I just noticed it.

[Taso1000]

I tried the 25.39 grain JSB's with the same settings and I stopped after 5 shots as I'm blowing air out the barrel after the pellet is gone.  The velocities were 913, 910, 894, 897 and 887 fps.  The 5 shots used 600 psi starting at 3000 psi.

This all points to the 34 grain JSB's are very close to the ragged edge.  The 15 inch barrel is a limitation to power but 51 fpe will work.   

Thanks,

Taso

[Zeddymon]

Some more, the onboard pump in action, relief valve still to be upgraded with better screw, it is designed to bring up to charge in the field and fill the gun, this is the prototype in bolt action, did see a side lever sentry also, little bigger receiver covering some of the power wheel indications but not in the way

Any more information on the pump up Sentry? Does the pump stay on the gun or just when needed? Is it a three stage pump?

 I realize this is an older post but I just noticed it.

it is a three stage pump, it stays on the gun, this seems like it needs a longer barrel, could be a great start to adding fps before getting into the valve work, i believe even a 28" barrel would still land short of the end of the gun, i dont know overall length though

[Zeddymon]

Does anyone know if the automatic safety can be disabled and be usable as a manual safety? 

Yes, I believe. I don't have a gen2 xs60 trigger group at hand to get you a pic, but, as the sentry appears to use it... and I have modded those for manual only.. it shouldn't be a problem.

  yeah!!!!!!

[stalwart]

Just received mine, a .25 HC Deluxe, today. Spent a pleasant evening measuring and pondering it's impending conversion to .30.

A little heavy, but solid... and the stock fits me perfectly.

Does anyone else think the bolt handle is a bit small? It seems to take quite a bit of pull to cock, enough to be uncomfortable. That, and the auto safety, are going to get some attention.

Well worth the money, and should be fun to customize.

[LeeGil]

I am just getting started back in the hobby and just purchased my first  PCP which is a Sentry. 25. Trying to get use to it first before I look into increasing the fps.  So far I love being able to have multiple shots with the PCP versus a break barrel or back in the days of my. 22 benjamin pump rifle. 

[Hoosier Daddy]

ATTA BOY LEE!

[Horatio]

Lee don’t mess around.

[Zeddymon]

new Sentry thread going :  https://www.gatewaytoairguns.org/GTA/index.php?topic=142052.new#new

the safety mod is included turning the auto safety into manual select for all those interested

[Big Rick]

I am hoping some of you fellow Sentry fans can help me figure out why my gun is a scatter gun. I have tried numerous pellets of varying weights and it still is throwing lead all over. In fact I`m wondering if I have a bad scope because this gun is acting like my Nitro Venom did whenever it blew out a scope. In my efforts to find where this gun wants to be I have lowered the power from 5 to 2 hoping my results would change as I did but no luck. Please help!